Deck 4 - GI Flashcards
- Q. What are the 3 main types of intestinal obstruction? Give an example of each
A. Intraluminal Obstruction
a. Tumour of the bowel (carcinoma, lymphoma)
b. Diaphragm disease: limits diameter of small bowel, caused by NSAIDS (fibrosis)
c. Meconium ileum
d. Gall stone ileus (inflamed gall bladder pushes on bowel, stone passes from gall bladder into small bowel and blocks it)
B. Intramural Obstruction
a. Inflammatory: Crohn’s (small bowel), diverticulitis (outpouching in sigmoid colon, faecal peritonitis can occur, low fibre diet)
b. Tumours
c. Neural: Hirschsprung’s disease (no dilation of colon in rectum – poor faecal movement – can lead to enterocolitis, presentation at birth)
C. Extra luminal Obstruction
a. Adhesions: between loops of bowel, often due to prev surgery (silica gloves), leads to fibrous adhesions – scar tissue
b. Volvulus: sigmoid colon, long mesentery can twist causing obstruction and occasionally tissue necrosis
c. Tumour: peritoneal deposits, often related to final stages of metastatic cancer
- Q. What comprise the embryological foregut, midgut and hindgut? Describe the nerve and blood supply of each.
a. Foregut = oesophagus, 2/3 duodenum, liver, gall bladder, pancreas, spleen
i. Blood supply: coeliac trunk
ii. Nerve supply: greater splanchnic nerve which arises from T5-T9, pain is usually felt anteriorly in the midline at this level i.e epigastrium
b. Midgut = 1/3 duodenum, jejunum, ileum, caecum, appendix, ascending colon, 2/3 transverse
i. Blood supply: superior mesenteric artery
ii. Nerve supply: lesser splanchnic nerve (T10 and T11) – referred to the periumbilical area
c. Hind gut = 1/3 transverse, rectum, upper anal canal
i. Blood supply: inferior mesenteric artery
ii. Nerve supply: lowest splanchnic nerve, T12 – referred to suprapubic area
- Q. Which parts of the GI tract are retroperitoneal?
A. Retroperitoneal organs are organs that are only covered by peritoneum on their anterior side (retro are more firmly attached than mesentery)
B. SAD PUCKER = suprarenal glands, aorta, duodenum last 2/3, pancreas, urethra, colon, kidney, (o)oesophagus, rectum
- Q. What is a volvus, where does this usually occur in the bowel?
A. A twist/rotation of a segment of the bowel – often occurs in sigmoid colon (then caecum)
a. A 360° twist -a closed loop obstruction is produced.
b. Fluid and electrolyte shifts into the closed loo
c. Increase in pressure and tension - impaired colonic blood flow
d. Ischaemia, necrosis, and perforation of the loop of bowel
- Q. What mechanisms of intestinal obstruction can occur?
A. Volvus: twisting – usually sigmoid
B. Adhesions: when abdominal structures stick to each other, (bowel loops of omentum, other solid organs, abdo wall)
C. Intussusception: telescoping one hollow structure into its distal hollow structure (small bowel into large bowel)
D. Atresia: absence of opening or failing of development of hollow structure
- Q. What occurs due to small bowel obstruction (pathophysiology and symptoms)?
A. Dilation - Increased secretions and swallowed air
B. More dilation – decreased absorption – mucosal wall oedema
C. Increased pressure – compression of intramural vessels
D. Ischaemia – perforation
E. Symptoms: anorexia, nausea, vomiting/distension with pain, fluid and electrolyte imbalance, hypovolemia, bacterial overgrowth faeculent vomiting
- Q. What occurs due to large bowel obstruction (pathophysiology and symptoms)?
A. Colon proximal to obstruction dilates, leads to increased pressure and decreased mesenteric blood flow
B. Mucosal oedema – transudation of fluid and electrolytes
C. Arterial blood supply is comprised – mucosal ulceration – full thickness necrosis – perforation – bacteria translocation – Sepsis
- Q. What can occur due to colonic volvulus?
A. Axial rotation at mesenteric attachments – 360 degree twist = closed lope obstruction
B. Fluid and electrolyte shifts into the closed loop: increase in pressure and tension: impaired colonic blood flow
C. Ischaemia, necrosis and perforation of loop in the bowel
- Q. Who is at a higher risk of small bowel obstruction?
o Adults – Adhesions (developed world)- previous surgery – Hernia ( developing world) – Crohns – Malignancy
o Children – Appendicitis – Intesussuption – Volvulus – Atresia – Hypertrophic pyloric stenosis
o Uncommon Causes – Radiation – Gall stones – Diverticulitis, appendicitis – Sealed small perforation, intra abdominal collection / abscess – Foreign Bodies ( Bezoars)
- Q. Who is at a higher risk of large bowel obstruction?
A. 90% colorectal maliganancy, (30% of colorectal malignanys present as LBO), » 5% Volvulus » 3% strictures Ischaemic, radiation, inflammatory, gynaecological other malignancy » 2% rare causes –FB, hernia, abscess » Functional obstruction - faecal impaction
B. Paeds: anatomical development, imperforate anus, hirshsprung’s disease
- Q. What is a hernia? How does it present? Describe four types of hernia – who do they most commonly affect?
A. An abnormal protrusion of viscus through normal or abnormal defects of body cavity
B. Presents as lump(appears and disappears), pain, discomfort
C. Inguinal hernia: mostly men, age-related
D. Femoral hernia: less common than inguinal, women
E. Umbilical hernia: young children
F. Incisional hernia: occurs when tissue protrudes through a surgical scar that is weak
- Q. Describe the anatomical location of the deep inguinal ring and the superficial inguinal ring
A. Deep inguinal ring: just above midpoint of the inguinal ligament
B. Superficial inguinal ring: just above and medial to pubic tubercle
- Q. Name two types of inguinal hernia
A. Direct: caused by weakness in posterior wall of the inguinal canal
a. Contents move through defect in posterior wall along the inguinal canal and through to superficial ring
B. Indirect: abdominal contents pass through deep inguinal ring, through inguinal canal and exit via superficial ring – more common
C. Both types exit superficial ring and emerge within the testes
D. Causes: increased intra-abdominal pressure, weakness of abdominal muscles - chronic cough, constipation, heavy lifting, advanced age, obesity
E. Present (GP): painless swelling in groin, often asymptomatic, lump may come and go, pain, change in bowel habit, constipation, burning sensation in groin, scrotal swelling (males)
- Q. Where are femoral hernias located? What are they prone to?
A. Comes through femoral canal below inguinal ligament
B. Appears below and lateral to pubic tubercle
C. Prone to incarceration and strangulation
- Q. How do umbilical hernias occur?
A. Occurs when tissue protrudes around the umbilicus: common in very young children, in most cases under 6m resolution will occur as the child grows older.
B. Risk factors in adulthood: obesity, heavy lifting, persistent coughing, multiple pregnancies
